Marine rudder

ABSTRACT

A combination of marine rudder and outboard or inboard/outboard marine engine of the type wherein the propeller is located below a horizontal cavitation plate which also usually has the engine exhaust outlet. The rudder is illustrated as being in the form of an attachment, having a mounting fork-like portion adapted to be bolted to the upper side of the cavitation plate. Integral with the mounting fork is a flat rudder blade which is characterized by having virtually all of its area disposed above the plane of the cavitation plate. The rudder blade is devoid of portions extending for any significant distance below the mounting fork, and the bottom portion of the rudder blade is located substantially in the same plane as the fork and engine cavitation plate. This arrangement provides for easier steering, and enables the rudder to be shifted readily to the straight ahead position from a tight turn position, especially when the craft is travelling at high speeds. The rudder blade is mostly disposed out of the turbulent water or wash created by the propeller. This turbulence or wash has a tendency to prevent easy manipulation and easy straightening of the rudder when the boat is travelling at high speeds in a tight turn position.

finite tates Patent Linsley 54 M NE RUBBER [72] Inventor: uglns F. Linsley, Westport, Conn.

[73] Assignees: Do i 2 F. Linsley; Helen E. Linsley,

Westport, Conn.

22 Filed: 0ct.22,1970

21 Appl.No.: 83,666

Primary ExaminerAndrew H. Farrell AttorneyH. Gibner Lehmann [451 Aug. 29, 1972 57 scr A combination of marine rudder and outboard or inboard/outboard marine engine of the type wherein the propeller is located below a horizontal cavitation plate which also usually has the engine exhaust outlet. The rudder is illustrated as being in the form of an attachment, having a mounting fork-like portion adapted to be bolted to the upper side of the cavitation plate. Integral with the mounting fork is a flat rudder blade which is characterized by having virtually all of its area disposed above the plane of the cavitation plate. The rudder blade is devoid of portions extending for any significant distance below the mounting fork, and the bottom portion of the rudder blade is located substantially in the same plane as the fork and engine cavitation plate. This arrangement provides for easier steering, and enables the rudder to be shifted readily to the straight ahead position from a tight turn position, especially when the craft is travelling at high speeds. The rudder blade is mostly disposed out of the turbulent water or wash created by the propeller. This turbulence or wash has a tendency to prevent easy manipulation and easy straightening of the rudder when the boat is travelling at high speeds in a tight turn position.

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MARINE RUDDER BACKGROUND This invention relates to marine rudder arrangements, and more particularly to a marine rudder combination with an outboard or inboard/outboard marine engine of the type having a horizontal cavitation plate, usually also provided with an exhaust. Prior rudders, usually produced as attachments, were arranged to be secured to a marine engine cavitation plate in such a manner that the rudder blade extended downward below the plane of the cavitation plate, being located directly in the wash or turbulent water area created by the propeller. This arrangement has a severe drawback, particularly when the boat is travelling at high speeds in a tight turn. Due to the wash or turbulence created by the propeller, an effect is had on the rudder blade by which there is required a considerable amount of force to straighten the rudder from the turn position when the craft is travelling at high speeds. In some situations where powerful engines are involved it has been found impossible to pull the rudder straight so as to take the craft out of a turn at high speeds, and the straightening of the rudder can only be accomplished after the engine power is reduced, to slow down the propeller and the craft.

SUMMARY The above disadvantages and drawbacks of prior rudders for outboard or inboard/outboard marine engines are obviated by the present invention, which has for one of its objects the provision of an improved rudder attachment for such engines, wherein the rudder can be easily straightened from a tight turn position when the craft or boat is travelling at high speed in a tight turn. This is accomplished by arranging the rudder blade so that virtually its entire area is mounted above the plane of the cavitation plate, rather than below the plane of the plate. The rudder attachment is constituted of a mounting fork which is preferably integral with the flat rudder blade, the latter extending upward from the plane of the mounting fork and the fork being arranged for attachment to the upper surface of the engine cavitation plate, as by bolting with screws. Essentially all of the rudder blade surface thus is located above the engine cavitation plate, resulting in a special ease of manipulation of the rudder for all conditions of travel of the craft, including tight turns at high or full speed.

Other features and advantages of the invention reside in the provision of an improved rudder attachment as above set forth, which is especially inexpensive to produce and manufacture, which is capable of being readily cast in metal or molded in plastic substance, and which is strong, sturdy and not likely to fail under severe conditions of use. Other advantages of the invention reside in a rudder as above set forth, which is easily attached to existing engines; and a rudder as above set forth, wherein the blade may be constituted so as to have flexibility whereby especially the rear or trailing portions of the blade flexes slightly under heavy loading, thereby to further minimize the likelihood of locking of the blade in a tight turn position and instead to facilitate the ease of manipulation of the rudder.

Still other features and advantages will hereinafter appear.

In the drawings illustrating several embodiments of the invention:

FIG. 1 is a top plan view of the improved rudder attachment of the invention, positioned for mounting on the cavitation plate of an outboard marine engine.

FIG. 2 is a side elevational view of the rudder attachment.

FIG. 3 is a rear elevational view of the rudder attachment.

FIG. 4 is a vertical section taken on the line 44 of FIG. 1.

FIG. 5 is a fragmentary top plan view of a rudder attachment constituting another embodiment of the invention, wherein the rudder blade is flexible and wherein the rudder can be molded from suitable plastic substance.

Referring to FIGS. 1-3 there is illustrated an outboard engine designated generally by the numeral 10, having a cavitation plate 12, an engine housing 14, a propeller 16, and an exhaust orifice 18. Arranged for mounting on the topside of the cavitation plate 12 is the present improved rudder attachment, designated generally by the numeral 20. The rudder attachment 20 comprises a flat rudder blade 22 and a mounting fork 24 secured to the lower edge portion 26 of the blade 22. The mountingfork 24 has a pair of flat, coplanar spaced-apart portions 28, 30 which project from the front edge portions 32 of the blade. The plane of the spaced portions 28 is at right angles to the plane of the blade 20, and is substantially at the same level as the bottom edge 26 of the blade. The spaced-apart mounting portions 28, 30 of the fork 24 have means to provide for their attachment by bolts to the cavitation plate 12 of the engine. Such means comprises mounting holes 34 adapted to receive bolts which pass through aligned openings (not shown) which are to be drilled in the cavitation plate 12.

The mounting fork 24 includes a yoke 36 which is joined to and extends along a large fractional part of the bottom edge portion 26 of the rudder blade 22. It will be seen in FIG. 2 that the plate 22 is devoid of portions which extend for any significant distance below the plane of the mounting fork 24. Preferably the rudder blade 22 and the fork 24 are constituted of a single integral piece of material. In FIGS. 1-4 the blade 22 and the fork 24 are shown as being in the form of a metal casting, and may be advantageously cast in aluminum or aluminum alloy.

For the purpose of strengthening the mounting fork 24 the latter is provided with a pair of elongate, parallel, reinforcing ribs 38 disposed on and extending upward from the upper surface of the fork. The reinforcing ribs 38 are disposed along the inner edges 40 of the spaced-apart portions 28, 30 of the mounting fork, as seen in FIG. 1. Preferably, streamlining is had by making the yoke 36 of the mounting fork so that it has substantially an arrowhead shape, as seen in FIG. 1.

The mounting fork 24, in attaching the rudder to an engine, is disposed above the upper surface of the cavitation plate as seen in FIG. 1, and used as a template to locate the holes which are to be drilled in the cavitation plate for the purpose of bolting the fork thereto. The ribs 38 have tapered end portions 42, 44 as seen in FIG. 2, to reduce turbulence and water resistance.

FIG, 5 illustrates another embodiment of the invention, wherein there is provided a rudder blade 22a which tapers to a thinner thickness at its trailing edge 46. Also, in FIG. 5 the mounting fork terminates at a more forward point or location on the bottom edge portion of the blade 22a. Thus there is had a greater or longer unsupported area of the blade 22a, as compared with the blade of FIGS. 1-3. The rudder attachment of FIG. 5 may be advantageously molded of a tough and flexible or resilient plastic, such as a plastic having fiberglass filler strands. It may be injection molded of methalmethacrylate which, when provided with the fiberglass filler, has a tensile strength of about 7,000 to 11,000 psi. and a compression strength of from 12,000 to 18,000 p.s.i. with an impact index of 0.3 to 05. Or, the blade and rudder attachment of FIG. 5 may be molded of polycarbonate without fibers, or of polypropylene with fiberglass. Other plastic substances are also capable of being used. The blade of FIG. 5 is seen to be thinner than the blade 20 of FIGS. L4, and is so constituted that it is resilient and can flex somewhat under the stresses imposed on it when the rudder is shifted to effect a turn of the craft or boat.

It will now be understood from the foregoing that l have provided a novel and improved rudder attachment which improves maneuverability, increases safety, steadies the boat or craft, is non-corrosive, universally adaptable to all types of motors or engines, and is easily attached by merely drilling four holes in the cavitation plate and bolting the attachment with non-corrosive stainless-steel bolts, for example. By virtue of the disposition of the blade 22 mostly above the cavitation plate 12 there is avoided the difficulty of hard pull-out from a tight turn when the craft is travelling at high speed. Instead, the rudder can be readily shifted from either tight-tum position to the straight ahead or other positions while the craft is maneuvering a high speed tight turn. This is in sharp contrast to prior rudders which were subjected to the wash or turbulence of the propeller and thereby made straightening of the rudder difficult if not impossible when the craft was travelling at high speed in a tight turn.

Variations and modifications are possible without departing from the spirit of the invention.

1 claim:

1. A combined impelling and steering construction for a boat, comprising in combination:

a. a propeller,

b. a cavitation plate disposed directly above the propeller,

c. a flat upright rudder blade,

d. a mounting fork secured to the lower edge portion of the rudder blade and having a pair of flat coplanar spaced-apart portions projecting from the front edge portion of the blade, the plane of said spaced portions being substantially horizontal and at right angles to the plane of the blade and being substantially at the same level as the bottom edge of the blade,

. said spaced-apart portions having means to provide for their attachment by bolts to said cavitation plate,

f. said mounting fork including a yoke joined to and extending along a large fractional part of the bottorn edge portion of the rudder blade, and said blade being devoid of portions extending for any significant distance below said mounting fork,

. said rudder blade being mounted by said fork in a location wholly above and rearward of the propeller and above the direct rearward wash from the propeller.

2. An attachment as in claim 1, wherein:

a. the rudder blade and mounting fork are constituted as a single integral piece.

3. An attachment as in claim 1, wherein:

a. the rudder blade is resilient and flexes when under lateral force while steering, as exerted by the water.

4. An attachment as in claim 1, wherein:

a. the mounting fork is disposed against the upper surface of the cavitation plate.

5. An attachment as in claim 1, wherein:

a. the said spaced-part portions and yoke of the mounting fork have elongate parallel ribs on their upper surfaces to increase the fork strength.

6. An attachment as in claim 5, wherein:

a. the said ribs are disposed along the inner edges of said spaced-apart portions.

7. An attachment as in claim 2, wherein:

a. the said yoke of the mounting fork has an arrowhead shape.

8. A combined impelling and steering construction for a boat, comprising in combination:

a. a propeller,

b. a cavitation plate disposed directly above the propeller,

c. a flat upright rudder blade,

(1. a mounting member secured to the lower edge portion of the rudder blade,

e. said mounting member being carried by said cavitation plate,

f. said mounting member including a yoke portion joined to and extending along a large fractional part of the bottom edge portion of the rudder blade,

g. said blade being devoid of portions extending for any significant distance below said mounting member,

h. said rudder blade being mounted by said mounting member in a location wholly above and rearward of the propeller and above the direct rearward wash from the propeller. 

1. A combined impelling and steering construction for a boat, comprising in combination: a. a propeller, b. a cavitation plate disposed directly above the propeller, c. a flat upright rudder blade, d. a mounting fork secured to the lower edge portion of the rudder blade and having a pair of flat coplanar spaced-apart portions projecting from the front edge portion of the blade, the plane of said spaced portions being substantially horizontal and at right angles to the plane of the blade and being substantially at the same level as the bottom edge of the blade, e. said spaced-apart portions having means to provide for their attachment by bolts to said cavitation plate, f. said mounting fork including a yoke joined to and extending along a large fractional part of the bottom edge portion of the rudder blade, and g. said blade being devoid of portions extending for any significant distance below said mounting fork, h. said rudder blade being mounted by said fork in a location wholly above and rearward of the propeller and above the direct rearward wash from the propeller.
 2. An attachment as in claim 1, wherein: a. the rudder blade and mounting fork are constituted as a single integral piece.
 3. An attachment as in claim 1, wherein: a. the rudder blade is resilient and flexes when under lateral force while steering, as exerted by the water.
 4. An attachment as In claim 1, wherein: a. the mounting fork is disposed against the upper surface of the cavitation plate.
 5. An attachment as in claim 1, wherein: a. the said spaced-part portions and yoke of the mounting fork have elongate parallel ribs on their upper surfaces to increase the fork strength.
 6. An attachment as in claim 5, wherein: a. the said ribs are disposed along the inner edges of said spaced-apart portions.
 7. An attachment as in claim 2, wherein: a. the said yoke of the mounting fork has an arrow-head shape.
 8. A combined impelling and steering construction for a boat, comprising in combination: a. a propeller, b. a cavitation plate disposed directly above the propeller, c. a flat upright rudder blade, d. a mounting member secured to the lower edge portion of the rudder blade, e. said mounting member being carried by said cavitation plate, f. said mounting member including a yoke portion joined to and extending along a large fractional part of the bottom edge portion of the rudder blade, g. said blade being devoid of portions extending for any significant distance below said mounting member, h. said rudder blade being mounted by said mounting member in a location wholly above and rearward of the propeller and above the direct rearward wash from the propeller. 